This invention relates to an alpine ski comprising a body which is composed of several elements and has on its underside a gliding surface and on its upper side a binding mounting area, and includes at least one upper chord element subjected primarily to pressure loads and at least one lower chord element subjected to tensile loads.
In an alpine ski of the type referred to which is known from DE 31 01 977 A1, the upper and the lower chord are each formed of at least two layers of different material and connected with each other by way of a core elastic in shear. In order to vary the bias or the surface pressure distribution in dependence upon the ambient temperature in conformity with the requirements, the layers in the upper and lower chord are arranged asymmetrically to the longitudinal center plane of the ski as regards their successive sequence and thickness used, and the thickness of layers having a large coefficient of linear expansion in the upper chord is greater than in the lower chord, while the thickness of layers with a smaller coefficient of linear expansion in the upper chord is smaller than in the lower chord. Regardless of the variations of surface pressure distribution due to temperature, in this known ski the surface pressure in the middle region of the ski is significantly greater than in the ski""s two end regions.
It is an object of the present invention to provide an alpine ski of the type initially referred to, which permits achieving a more uniform surface pressure distribution over the ski""s gliding surface.
According to the present invention, this object is accomplished in that in the ski""s middle region the upper chord element is shaped in the manner of a flat, upwardly curved arc extending in the longitudinal direction of the ski and spanning the lower chord element, and the arc of the upper chord element is adapted to deflect in the direction of the lower chord element in dependence upon the load exerted by the binding, and the upper chord element is supported in the end regions of the ski in such a way that a displacement of the ends of the upper chord element resulting from the deflection of the arc increases the load carrying share of the end regions of the ski.
The alpine ski of the present invention permits achieving a uniform pressure distribution over the full length of the ski""s gliding surface, which depends on the respective load to a reduced degree, and a dynamic balance of bumps. This results in a maximum possible contact length of the ski edges, in addition to considerably improving both the tracking stability and the response to steering impulses of the skier. Another advantage is that impact loads emanating from the slope can be effectively damped by the bending elasticity of the upper chord element.
The deflection of the arched upper chord element is achievable by the provision of a cavity in the interior of the ski underneath the arc, the amplitude of deflection being limitable to a maximum value by suitably dimensioning the height of the cavity. According to a further proposal of the invention it is possible to substitute for the cavity a core of an elastic and/or elastically compressible material which is arranged between the arc of the upper chord element and the underlying lower chord element. In this arrangement the deflection and the vibrational behavior of the upper chord element can be influenced by the deformation resistance of the elastic or elastically compressible material. Furthermore, to influence the vibrational behavior the upper chord element can be arranged to take support on the lower chord element in longitudinal direction through friction elements and/or damping elements of an elastomeric material.
For force application the upper chord element has in the binding area preferably devices for attachment of the binding components. In a possible configuration the upper chord element has in the binding mounting area a plate bounding the ski upper side or embedded therein, to which plate the binding components are securable.
The alpine ski of the present invention may comprise one upper chord element and one lower chord element. However, it may also be advantageous to arrange in the ski body several upper chord elements and/or lower chord elements in juxtaposed relation to each other. An advantageous embodiment provides for the lower chord element to be made of a thin-walled strip of sheet metal, fiber material or fabric of high tensile strength. Preferably, the upper chord element may be composed of one or several rods or tubes or, alternatively, plate-shaped elements which are made of a pressure-resistant material, for example, metal, fiber-reinforced plastics, wood or similar material and which, owing to their shape and, if applicable, their embedding in the ski body, are sufficiently safe against buckling.
The upper chord element and the lower chord element preferably extend over the full length of the ski""s gliding surface. In this arrangement the upper chord element may be arranged above the lower chord element over the entire length. In an advantageous configuration of the invention it is envisaged that the upper chord element crosses the lower chord element in one of the two end regions of the ski, subsequently continuing beneath the lower chord element. Still further, provision can be made for the upper chord element to cross the lower chord element twice in an end region of the ski, so that the upper chord element extends above the lower chord element in the middle of the ski and in the outer end region, while extending beneath the lower chord element in the area in-between. In this configuration the lower chord element or the upper chord element may have a respective cutout at the crossings through which the other element is passed.
Preferably the upper chord element and the lower chord element are fixedly connected with each other only at their ends. In the zone therebetween, the elements are carried in the ski body""s material surrounding them. Sections of the elements may also be arranged on the ski body so as to be exposed, that is, visible and accessible from the outside. According to the present invention the upper chord element is guided in the ski body so as to be able to execute a longitudinal movement, though small, relative to the ski body.
The ski body material surrounding the elements is preferably a filler of low density, for example, a foamed plastics material, a fiber material or a fabric referred to as spacer fabric. According to the present invention the ski body may also include a box of mechanical resistance in which the elements surrounded by filler material are arranged.